| The past few years have seen the Global Positioning System (GPS) reach maturity with the completion of the satellite constellation, the increased availability and affordability of user equipment and the adoption of GPS as the technology of choice in a number of positioning and navigation applications. The increasing demand for observations from reference stations with accurate coordinates and the need to maintain and upgrade a uniform and consistent spatial reference system is leading to the deployment of continuously operating GPS tracking networks, more commonly referred to as GPS Active Control Systems.;This thesis considers three particular areas of interest in the implementation and use of Active Control Systems. First, "Canada's Active Control System (CACS) - Data Acquisition and Validation" describes the status of CACS as its existed in 1993, proposes an approach to assessing the quality of GPS observations and details its implementation. Then, "Precise Positioning with a Difference" describes and evaluates the use of precise GPS orbit and clock products for precise pseudorange point positioning. Finally, "Positions for GIS: Getting them Right the First Time" considers issues regarding the integration of GPS derived positions in Geographic Information Systems (GIS). (Abstract shortened by UMI.). |
